The following is
some of the well-known Unix flavors, with links to their official home pages.
AIX - IBM
BSD/OS (BSDi) - Wind River
CLIX - Intergraph Corp.
Debian GNU/Linux - Software in the Public Interest, Inc.
Tru64 Unix (formerly Digital Unix) - Compaq Computer Corp.
DYNIX/ptx - IBM (formerly by Sequent Computer Systems)
Esix Unix - Esix Systems
FreeBSD - FreeBSD Group
GNU Herd - GNU Organization
HAL SPARC64/OS - HAL Computer Systems, Inc.
HP-UX - Hewlett-Packard Company
Irix - Silicon Graphics, Inc.
Linux - several groups several
LynxOS - Lynx Real-Time Systems, Inc.
MacOS X Server - Apple Computer, Inc.
NetBSD - NetBSD Group
NonStop-UX - Compaq Computer Corporation
OpenBSD - OpenBSD Group
OpenLinux - Caldera Systems, Inc.
Openstep - Apple Computer, Inc.
Red Hat Linux - Red Hat Software, Inc.
Reliant Unix - Siemens AG
SCO Unix - The Santa Cruz Operation Inc.
Solaris - Sun Microsystems (now ORACLE)
SuSE - S.u.S.E., Inc.
UNICOS - Silicon Graphics, Inc.
UTS - UTS Global, LLC
AIX - IBM
BSD/OS (BSDi) - Wind River
CLIX - Intergraph Corp.
Debian GNU/Linux - Software in the Public Interest, Inc.
Tru64 Unix (formerly Digital Unix) - Compaq Computer Corp.
DYNIX/ptx - IBM (formerly by Sequent Computer Systems)
Esix Unix - Esix Systems
FreeBSD - FreeBSD Group
GNU Herd - GNU Organization
HAL SPARC64/OS - HAL Computer Systems, Inc.
HP-UX - Hewlett-Packard Company
Irix - Silicon Graphics, Inc.
Linux - several groups several
LynxOS - Lynx Real-Time Systems, Inc.
MacOS X Server - Apple Computer, Inc.
NetBSD - NetBSD Group
NonStop-UX - Compaq Computer Corporation
OpenBSD - OpenBSD Group
OpenLinux - Caldera Systems, Inc.
Openstep - Apple Computer, Inc.
Red Hat Linux - Red Hat Software, Inc.
Reliant Unix - Siemens AG
SCO Unix - The Santa Cruz Operation Inc.
Solaris - Sun Microsystems (now ORACLE)
SuSE - S.u.S.E., Inc.
UNICOS - Silicon Graphics, Inc.
UTS - UTS Global, LLC